Copolymers of propylene and hexene-1 having a low 1-hexene content are known in the art. WIPO Pat. App. Pub. No. WO 2006/002778 relates to a random polymer of propylene and 1-hexene containing from 0.2 to 5 wt % of recurring units derived from hexene-1. The propylene-hexene-1 polymer exhibits a broad molecular weight distribution of a monomodal type.
WIPO Pat. App. Pub. No. WO 2009/083500 relates to plastic tanks made from propylene copolymers of propylene and hexene-1. The 1-hexene derived units range from 0.5 wt % to 5 wt %. This document is silent regarding the modality of the copolymers; however, the copolymer exemplified has a distribution of the monomodal type.